The specifc aim of this research is to develop new synthetic methodology and strategies for the synthesis of highly oxygenated degrated triterpenoids such as the quassinoids, and various heterocyclic systems, in particular indole alkaloids. A central feature is the convergent nature of the proposed syntheses through the use of intramolecular cycloaddition reactions. The synthesis of indole alkaloids describes a new and versatile way of making these molecules that has no previous analogy in this area.